JP2869125B2 - Manufacturing method of ball screw - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of manufacturing a ball screw used for positioning of a machine tool by numerical control or for a steering gear for an automobile.

(Prior art) Conventionally, a ball screw of this type has been rolled while pressing a pair of flat dies, round dies, or thread dies such as a segment die and a round die against a cylindrical screw surface, and the ball surface has been wound on the die surface. The surface of the material is plastically deformed by the provided threads, and the threads are formed, that is, the thread is formed by a so-called rolling method, mechanical grinding with a lathe or a hobbing machine, or the like.

(Problems to be Solved by the Invention) However, the conventional rolling method and mechanical grinding have a limit in removing a useless portion inside the shaft, and a sufficient result is produced in manufacturing a hollow ball screw. There was a problem that could not be given.

An object of the present invention is to provide a method of manufacturing a ball screw capable of manufacturing a lightweight and hollow ball screw by eliminating the useless portion of the inner surface of a shaft in order to improve the above-mentioned problem.

(Means for Solving the Problems) In view of the conventional problems as described above, the present invention relates to a method of inserting a hollow pipe into a hollow bulge type in which a convex screw is spirally formed on an inner peripheral surface. By applying pressure to the inside of the hollow pipe, the outer peripheral surface of the hollow pipe is pressed against the inner peripheral surface of the bulge type to form a thread groove following the convex screw, and then the hollow pipe is turned. A ball screw manufacturing method for manufacturing a hollow ball screw by taking it out of the bulge mold.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, a hollow bulge mold 3 having a helical convex screw 1 for forming a ball screw formed on an inner peripheral surface thereof is prepared, and a hollow pipe 5 is inserted therein.

As shown in FIG. 3, a U-shaped side cover 7 is fitted to the end surface of the bulge mold 3, and a wrench 9 is inserted through a regular hexagonal protruding piece 9 (see FIG. 4) formed on the outer surface of the side cover 7. The side cover 7 is screwed to the bulge mold 1 by a fastener such as.

A frame 11 concentric with the outer edge of the side cover 7 is formed inside the side cover 7, and the hollow pipe 5 is fitted around the frame 11 to fix the end of the hollow pipe 5.

With the above configuration, high-pressure oil is injected from the other end face (not shown) of the hollow pipe 5, and the pressure uniformly acts from the inside to the outside of the hollow pipe 5 by the oil pressure, and as shown in FIG. The inner surface of the hollow pipe 5 is expanded, the outer peripheral surface thereof is pressed against the inner surface of the bulge mold 3, and a thread groove is formed on the outer peripheral surface of the hollow pipe 5 following the convex screw 1.

Note that such bulging is performed by cold working.
After a lapse of a certain period of time (according to experience), the pressure oil in the hollow pipe 5 is discharged, and the hollow pipe 5 is pulled out from the bulge mold 3 while turning the hollow pipe 5 from the other end thereof. Shaped ball screws can be manufactured.

As described above, according to the ball screw manufacturing method of the present embodiment, the end face of the bulge mold 3 is closed by the side lid 7, the hollow pipe 5 is inserted into the bulge mold 3, and the end face is attached to the side lid 7. It is fixed, high-pressure oil is injected from the inside of the hollow pipe 5, a uniform pressure is applied to the inner surface of the hollow pipe 5 by the oil pressure, and the outer surface of the hollow pipe 5 is pressed against one internal thread of the inner surface of the bulge type 3 (bulge processing). Then, by forming an external thread surface and then removing it while turning, it is possible to manufacture a lightweight and uniform-thickness ball screw without a trace of a bulge-type joint.

The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes.

For example, in this embodiment, the end face of the bulge mold 3 is closed by the side cover 7 as shown in FIGS. 3 and 4, and the hollow pipe 5 is fitted to the frame 11 of the side cover 7. Other means may be employed without departing from the spirit of the invention.

In addition, although the description has been made by injecting the pressure oil into the hollow pipe 5 as a manufacturing means of the ball screw, the invention is not limited to the pressure oil, and for example, pressurized air may be used. In short, what is necessary is just to expand the hollow pipe 5 by pressure.

[Effects of the Invention] As can be understood from the above description of the embodiment, in short, the present invention provides a hollow bulge type (3) in which a convex screw (1) is spirally formed on an inner peripheral surface. Hollow pipe (5)
Is inserted, pressure is applied to the inside of the hollow pipe (5), and the outer peripheral surface of the hollow pipe (5) is pressed against the inner peripheral surface of the bulge type (3) to form the convex screw (1). This is a method of manufacturing a ball screw in which a thread groove is formed in accordance with the shape, and thereafter, the hollow pipe (5) is taken out from the bulge mold (3) while being swirled to manufacture a hollow ball screw.

That is, according to the present invention, a hollow pipe 5 is inserted into a hollow bulge mold 3 in which a convex screw 1 is spirally formed on an inner peripheral surface, and a pressure is applied to the hollow pipe 5 to form the hollow pipe 5.
By pressing the outer peripheral surface of the bulge mold 3 against the inner peripheral surface of the bulge mold 3, a screw groove is formed on the outer peripheral surface of the hollow pipe 5 in accordance with the convex screw 1, and thereafter, after being turned from the bulge mold 3, The hollow pipe 5 is withdrawn.

That is, in the present invention, since the bulge mold 3 is not a split mold but a hollow mold, when a thread groove is machined on the outer peripheral surface of the hollow pipe 5, the outer peripheral surface of the hollow pipe 5 has This makes it possible to easily produce a hollow ball screw with high precision without causing traces of the ball screw.

[Brief description of the drawings]

FIG. 1 is a side cross-sectional view of a main part of one embodiment according to the present invention before starting processing, FIG. 2 is a side cross-sectional view of the main part after starting processing in FIG. 1, and FIG. FIG. 4 is a sectional side view showing an attached state of an end portion of a work before starting machining according to an embodiment of the present invention, and FIG. 4 is a view taken in the direction of arrows IV-IV in FIG. 1 ... convex screw, 3 ... bulge type, 5 ... hollow pipe 7 ... side lid, 9 ... projecting piece, 11 ... frame

Claims (1)

(57) [Claims] 1. A hollow pipe (5) is inserted into a hollow bulge type (3) having a spirally formed screw (1) on its inner peripheral surface, and then the hollow pipe (5) is inserted into the hollow pipe (5). Pressure is applied to the outer peripheral surface of the hollow pipe (5) against the inner peripheral surface of the bulge mold (3) to form a thread groove following the convex screw (1). (5) A method for manufacturing a ball screw, wherein the ball screw is taken out from the bulge mold (3) while rotating to manufacture a hollow ball screw.